Shimano prides itself on seamless shifting and it's specs are quite conservative to preserve that reputation. With a little sensible caution and a chain catcher you should be able to replace the 26 with a 22. 22/36 is a big drop. If you are just going to replace a single chainring, I'd suggest a 24 rather than 22. When cogs are that small, even 2 teeth is a much smaller gear. 48/36/24 is a very standard touring triple ring config.
If you've got a bit more coin to spend I would highly recommend going to a Deore XT 10 speed triple, it comes with 24/32/42 and can easily be swapped out for your crank and a 22t replacement works just fine. It will work fine with your current 9spd drive train and provide a more reasonable set of gears. I did this with my 2017 Haanjo Exp which has very similar specs.
That price is kind of high IMHO, you should be able to find it cheaper.
Another change you might consider is switching to a 12-36 9 speed cluster in the rear. This will work just fine with your components and provide more usable gears in the middle and high chainrings. The difference between 26/32 and 26/36 will be significant. You'll need to learn what the "B" adjustment is on a derailleur to get this cluster working properly.
That price is about the same as a 22t chainring and probably the cheapest way to get lower gears on that bike.
With a Wolftooth Roadlink, you can even go as big as 40t in the back with a 9 speed Deore derailluer. Finding a 9 speed cluster with a 40t isn't cheap, but it is possible.
While it's getting better, standard gearing that comes with most bikes makes very little sense for the novice rider. 48/11 is a huge gear and if you've got steep/long hills 26/32 is not low enough to climb w/o going into the red zone. Especially on a touring bike that is meant to carry loads.
There is a point where the gearing gets too low to ride. It depends a lot on the terrain and rider, I found that 22/40 was too low for me even on steep dirt. But having a 24/40 works for me for long fire roads at altitude.
There is a lot to learn and you may outgrow your gears, but the best investment you can make in gear starting out is gears that work for YOU!, not tour de france racers.